Reactor for preparation of chlorohydrins of 1,2-glycols

ABSTRACT

A chemical reactor comprising a generally cylindrical reaction vessel, a series of three jackets defining a central chamber and three annular chambers within the reactor, means for feeding a first gaseous reactant, such as chlorine, to the lower portion of the first annular chamber to displace liquid reaction medium therein to the centrally disposed chamber for flow downwardly therethrough, means for introducing a second gaseous reactant, such as an ethylenic hydrocarbon, to the third annular chamber to cause flow of the liquid reaction medium therein upwardly therethrough to the second annular chamber for reaction with the reaction product of the chlorine and water in the liquid reaction medium to thereby minimize the production of chlorinated alkanes.

United States Patent Bouchet H lMarch 20, 1973 REACTOR FOR PREPARATIONOF [56] References Cited CHLOROHYDRINS OF 1,2-GLYCOLS UNITED STATESPATENTS [75] Inventor: Robert Bouchet, Martigues, France 3,426,095 2/1969 Passley ..23/288 E X [73] Assignee: Naphtachimie, Paris, FrancePrimary ExaminerJarnes H. Tayman, Jr. [22] Ffled' 1971Attorne'y-McDougall, Hersh & Scott 21 Appl. No.: 105,917

[57] ABSTRACT A chemical reactor comprising a generally cylindrical [30]Forelgn Apphcatlon Pflonty Data reaction vessel, a series of threejackets defining a Jan. 13, 1970 France ..7000985 central chamber andthree annular chambers within the reactor, means for feeding a firstgaseous reactant, such as chlorine, to the lower portion of the firstannu- [52] US. Cl. ..23/285, 23/288 E, 23/283, lar chamber to displaceliquid reaction medium 261/76, 261/123, 260/683 R, 260/633, therein tothe centrally disposed chamber for flow 260/643 R 260/660, 260/694,259/4, 259/95 downwardly therethrough, means for introducing a [51] Int.Cl. ..C07c 17/02, B0'1j l/00 second gaseous reactant, such as an y e c[58] Field of Search ..23/285, 288 E, 252 R, 260, hydrocarbon, to thethird annular chamber to cause flow of the liquid reaction mediumtherein upwardly therethrough to the second annular chamber for reactionwith the reaction product of the chlorine and water in the liquidreaction medium to thereby minimize the production of chlorinatedalkanes.

5 Claims, 1 Drawing Figure PATENTEnmzoms I INVENTOR. 1610A? 6044;640:-BY/Ife Eats/J14 h uesb Soft REACTOR FOR PREPARATION OF CHLOROHYDRINS OFl,2-GLYCOLS This invention relates to a chemical reactor and moreparticularly to a reactor for the continuous preparation ofmonochlorohydrins of 1,2-glycols from chlorine, ethylenic hydrocarbonsand water. The reactor is particularly well suited for the preparationof 1,2- propylene glycol monochlorohydrin, with a view to preparing1,2-propylene oxide.

The manufacture of a l,2-glycol monochlorohydrin from chlorine, anethylenic hydrocarbon and water generally involves first preparing ahydrochloric solution of hypochlorous acid by reacting chlorine andwater, and then contacting the ethylenic hydrocarbon with this solution.The hypochlorous acid reacts with the ethylenic hydrocarbon to form themonochlorohydrin of the corresponding glycol. The process can be carriedout continuously by causing chlorine to react on the reaction liquid ina first vessel, then adding the ethylenic hydrocarbon to the reactionliquid from the first vessel in a second vessel, and finallycontinuously removing a small fraction of the reaction liquid from thesecond apparatus and recycling the remaining fraction of the reactionliquid to the chlorine-water reaction vessel while adding water tocompensate for the water consumed.

In order to avoid the formation of undesirable byproducts, such aschloroalkanes, it is necessary on the one hand to limit the chlorinecontent of the reaction liquid generally by using high liquidrecirculating rates, and on the other hand, to avoid as far as possiblethe presence of bubbles of ethylenic hydrocarbon in the recycledreaction liquid. It is difficult in practice to obtain the aboveconditions simultaneously, since high recirculating rates for thereaction liquid require a large supply of the liquid, and a large supplycreates turbulence which encourages the formation of small bubbles ofethylenic hydrocarbon and the carrying of the bubbles towards thereaction of chlorine with water.

In order to resolve these difficulties it has been proposed tointerconnect the reaction vessels by means of pipes of large section, asa means of limiting the formation of turbulence as far as possible. Thishas only partially resolved the difficulties mentioned, since the flowof liquid in the pipes necessarily causes contractions in the flowingliquid, which encourages the formation of turbulence. Moreover, thevarious reagents are not distributed homogeneously, due to the fact thatthey are introduced locally. This method also involves seriousdifficulties, partly because of the large quantities of liquid whichhave to be circulated between the reaction vessels, particularly forinstallations with an average or large production capacity, and partlybecause of the need to use corrosion resistant construction materials,such as titanium, which has the drawback of being ill-adapted to makingcomplex apparatus.

This and other objects and advantages of the invention will appear morefully hereinafter, and, for purposes of illustration, and not oflimitation, an embodiment of the invention is shown in the accompanyingdrawing.

The reactor according to the invention provides a simple, effectivesolution to the difficulties described above. The reactor, which isapplicable to the continuous preparation of monochlorohydrins of1,2-glycols from chlorine, an ethylenic hydrocarbon and water,essentially comprises a cylindrical casing with a vertical axis, threecylindrical jackets located inside the casing and substantially coaxialwith one another and with the casing, the first of these jackets,located nearest to the axis of the reactor, and the third jacket beinginterconnected by their lower portions, and the second jacketcommunicating via its upper portion with the outside of the casing, thethree jackets and the casing thus defining three annular spaces and onecylindrical space which are coaxial and which communicate successivelywith one another via their upper or lower portions; the reactor furthercomprises a device located towards the lower end of the peripheralannular space for the continuous introduction of the ethylenichydrocarbon, a device located in the inner annular space for thecontinuous introduction of the chlorine, a device for the introductionof the water and a device located in the lower portion of theintermediate annular space for the continuous removal of a fraction ofthe reaction medium containing the monochlorohydrins of l,2-glycols.

A preferred embodiment of the invention is shown in section in theFIGURE. In this figure, the casing 1 and the three jackets 2, 3, and 4,of the apparatus are all circular in section and define a cylindricalspace 5 and annular spaces 6, 7 and 8. The casing 1 contains a vent 9through which the excess ethylenic hydrocarbon escapes. The intermediatejacket 3 is made up of two cylindrical portions 3a and 3b connected by afrustoconical portion 3c, the portion 3a being larger in section thanthe portion 3b. The non-dissolved chlorine and the inert gases liable toaccompany it leave the reactor from inside the portion 3b of the jacket3. The portion 3b comprises a chlorine washer 10 which is sprayed, bymeans of the pipe 11, by the water required for the operation. The innerjacket 2 is limited in height to the base of the frusto-conical portionof 3c of the jacket 3. The jackets 2 and 4 are connected in their lowerportions by a continuous spout 12. The upper part of the jacket 4 isimmersed in the reaction liquid, the level of which is represented bythe line 13; the depth of the liquid is substantially equal to thedistance between the jacket 4 and the casing 1, so that the reactionliquid flowing from the annular space 8 to the annular space 7 does notundergo any contraction. In order that the flow should be disturbed aslittle as possible, the upper part of the jacket 4 is equipped with arounded flange 14. The reactor is fed with chlorine by means of the pipe15 and the diffuserlfi which distributes the chlorine over a section ofthe annular space 6; the reactor is fed with ethylenic hydrocarbon bymeans of a pipe 17, an annular distribution box 18 and diffusers 19,spread over a section of the annular space 8; these diffusers 19, two ofwhich are shown in the FIGURE at 19a and 1%, are in the form of porousporcelain or ceramic filter candles held in position by a strap (notshown). The pipe 10 serves to evacuate a fraction of the reaction mediumcontaining the 1,2- glycol monochlorohydrin.

The reactor according to theinvention is used in the Having describedthe basic concepts of the invention, reference is now made to thefollowing specific example as an illustration of the use of theapparatus of hydrocarbon, both in gaseous form, are introduced I throughpipes 15 and 17, respectively. The gas bubbles,

rising into the annular spaces 6 and 8, create an ascending movement ofthe liquid present in the spaces according to the known principle of theairlift. While 1 the chlorine is inthe annular space 6 it dissolvesparvti ally in the water, to form, in solution, hypochlorous acid andhydrochloric acid. The excess chlorine escapes from the reactor throughthe upper part of the space this excess chlorine is washed and partiallydissolved in the washer 10 by the water introduced through the pipe (Theaqueous solution leaving the annular space 6 passes into the cylindricalspace 5, in which it descends until it passes into the cylindrical theinvention in the preparation of the chlorohydrin of propylene glycolusing propylene as the ethylenic hydrocarbon.

EXAMPLE 1 Into a reactor made of titanium and constructed as shown inthe FIGURE, there are introduced 180 parts by'w'eight of water; when theapparatus has been purged-with nitrogen, 4.63 parts by weight per hourof chlorine gas are introduced through the pipe and 4.85 parts by weightof propylene gas through the pipe 17. The washer 10 is sprayed with117.4 parts by weight of water. When balanced operating conditions space5, in which it descends until it passes into the annular space 8. inthis space the liquid is moved upwards by the bubbles of the ethylenichydrocarbon. Uniform distribution of the ethylenic hydrocarbon caneasily be obtained over each section of the space 8, because of theannular shape of the latter. Moreover, since this space can easily belarge in section because of its peripheral position, it is possible tofeed large supplies of ethylenic hydrocarbon into the reactor. Duringthe ascent into the space 8, the ethylenic hydrocarbon is partiallydissolved in the hydrochloric solution of hypochlorous acid coming fromthe space 5, to form 1,2-glycol,monochlorohydrin which remains insolution. The excess ethylenic hydrocarbon leaves the reactor throughthe vent 9. in the upper part of the annular space 8 the liquid passesinto the upper part of the annular space 7, the broad section of whichencourages the tranquilizing ofthe liquid and the degassing of thenon-dissolved ethylenic hydrocarbon. The liquid then descends into thelower part of the space 7 and re-enters the space 6. A fraction of thereaction liquid is ex- I tracted from the reactor through the pipe 20;this fraction is then treated in known manner, with a view to treatingthe l ,2-glycol monochlorohydrin which it contains.

The reactor according to the invention has several advantages overpreviously known apparatus, in the field of both construction and use.Thus, the reactor of the invention, particularly when it is shaped as 'acylinder'ofrevolution; is made up of members which are simplyconstructed and easily assembled, even with materials such as titanium.This single reactor alone replaces the complex installations previouslyknown for the preparation of 1,2-glycol monochlorohydrins. Thisalso'makes it easier to solve the problems of vibration areestablished,the temperature is 58C. and the pressure 1.4 bars. 124 parts by weightper hour of a solution containing 4.5 percent by weight of chlorohydrinof the propylene glycol are tapped through the pipe 20. Al-

lowing for the fact that 2.1 parts by weight per hour of non-consumedpropylene which can be recycled are recovered through the vent 9, thechemical yield from the conversion of propylene to chlorohydrin of thepropylene glycol is 90.2 percent. The chloropropane fonned isapproximately 0.076 molecule per molecule of chlorohydrin (9. l percentby weight).

' However, it will be understood that use can be made of a variety ofethylenic compounds. Preferred ethylenic compounds are olefinscontaining two to eight carbon-atoms.

it will be apparent that various changes and modification can be made asto the details of procedure, constructionand use without departing fromthe spirit of the invention, especially as defined in the followingclaims.

I claim: I

l. A chemical reactor comprising a vertically disposed, generallycylindrical reaction vessel adapted to contain a liquid reaction medium,a first jacket defining a central chamber open at the lower portionthereof for communication with the vessel, a second jacket about thefirst jacket defining a first annular chamber between the first andsecond jackets and terminating in means for introducing a liquidreaction to the upper portion thereof, the upper portion of the firstannular chamber communicating with the upper portion of the cylindricalchamber, means for introducing a gaseous first reactant into the lowerportion of the first annular chamber to displace liquid in the firstannular chamber upwardly therethrough, the second jacket including aninverted frusto-conical portion, with the first jacket terminating atsubstantially the level of, the base of the frusto-conical portionwhereby liquid flowing through the first annular chamber flows upwardlyinto a frusto-conical zone defined by'the frusto-conical portion tominimize turbulence, a third jacket about the second jacket defining asecond annular chamber therewith, the lower portion of which'communicates with the lower portion of the first annular chamber, thethird jacket also defining a third annularthe lower portion of the firstannular chamber, means for feeding a second gaseous reactant to thelower portion of the third annular chamber for contact with liquidtherein from the cylindrical chamber and to displace the liquid upwardlyfor passage to the second annular chamber, and means for removing aportion of the liquid from the second annular chamber.

2. A reactor as defined in claim 1 wherein the means for introducing thefirst gaseous reactant to the first annular chamber includes a pluralityof diffusers spaced about the chamber.

3. A reactor as defined in claim 1 wherein the third jacket is formed atits upper portion in an inwardly extending lip to minimize theturbulence of liquid from the column to wash gases from thefrusto-conical portion.

5. A reactor as defined in claim 1 wherein each of the jackets aresubstantially cylindrical and coaxial each with the other.

2. A reactor as defined in claim 1 wherein the means for introducing thefirst gaseous reactant to the first annular chamber includes a pluralityof diffusers spaced about the chamber.
 3. A reactor as defined in claim1 wherein the third jacket is formed at its upper portion in an inwardlyextending lip to minimize the turbulence of liquid from the secondannular chamber to the third annular chamber.
 4. A reactor as defined inclaim 1 which includes a counter-current washing column on the upperportion of the frusto-conical portion and means to add liquid to thecolumn to wash gases from the frusto-conical portion.
 5. A reactor asdefined in claim 1 wherein each of the jackets are substantiallycylindrical and coaxial each with the other.